Circuit control system



1931. J. c. BURKHOLDER 1,803,916

CIRCUIT CdNTROI) SYSTEM Filed Nov. 15, 1925 v lnven/or: I John C. Bur/(holder.-

Patented June 9, 1931 UNITED STATES PATENT OFFICE JOHN C. BURKHOLDER, OF MONTCIiAIR,

NEW JERSEY, ASSIGNOR TO WESTERN ELEC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK CIRCUIT CONTROL SYSTEM Application filed November 13, 1925. Serial No. 68,823.

This invention relates to circuit control systems, and more particularly to means for controlling the operation of circuit switching devices.

In many electrical systems, such, for example, as electrical signaling systems, it is desirable or necessary to provide apparatus such as potentiometers for varying the volume of the transmitted waves and to be able to control the adjustment of such apparatus from a distance. Or again, the proper operation of a given circuit may involve the s1- multaneous control of the ad ustment of 011- cuit apparatus located at a plurality of widely separated points. A specific illustration of a system wherein such control is necessary is one for transmitting signals from a pickupstation, such as a theater, over a wire line to a radio broadcasting station.

The limited signal volume capacity of the repeaters or other apparatus included in a signal line, similar to that just described, makes it necessaryto reduce the volume of signals applied to the line at the transmitting end and to subsequently restore the volume to its original value at the receiving end, so that the quality of signals is unimpaired by the volume control operation.

The present invention has for an object the control of adjustable circuit elements.

Another object is to cause the simultaneous adjustment of separate apparatus elements in opposite senses. V p y A further object is to electrically control the magnitude and sense of the movement of a movable body- A more specific object is to control the volume of signals and to cause a variation in volume at one point while producing an opposite variation in volume at another point, so that the resultant volume change will be negligible.

A feature of the invention is a control switch adapted to transmit releasing and driving impulses to motor mechanisms for causing rotation thereof in either direction.

A further feature is a motor having a rotatable member and driving and releasing mechanisms therefor, the direction of rotation of the member being determined by The invention, in its broader aspects, in-

volves the control of the direction of rotation of a member such as a rotary switch in accordance with the polarity of electrical impulses supplied to electromagnetic driving devices, and the control of the degree of movement of the member in accordance with the number of impulses in a sequence supplied to a releasing device.

More specifically a manually operated sender switch is adapted to supply positive or negative impulses, according to the direction in which it is rotated, to a line including one or more solenoidal windings in series. Armatures associated with the solenoids are connected to a driving gear for rotating a switch arm through an are over contacts which may be connected to difi'er ent points on'a resistor included in a circuit over which signals are to be transmitted.

The sender switch may also be adapted to transmit at the same time a series of impulses, the polarity of which is determined y the direction in which the sender switch is turned and the number of which is determined by the magnitude of the are through which the switch is rotated' These impulses are supplied to releasing magnets associated with the respective motors to determine the number of steps that shall be taken by each switch.

The resistor elements may be included, for example, in a line connecting a sound pickup transmitter to a radio broadcasting transmitter, one resistor being adapted to function as a potentiometer for controlling the volume of signals at the sending end, the other resistor being adapted to function as a potentiometer for controlling the volume of signals in an opposite sense at the receiving end of the line. In this way, the volume of signals supplied to the line may be confined to the signal volume capacity of the line, and the signals at the receiving end of the line may be restored to the volume characteristics substantially unaltered, of the signal'waves supplied by the pickup transmitter. Y

Additional features, objects and advan:

device 10, a volume control potentiometer 11,

a wire linel2, a. second volume control. potentiometer 13, and a radiotransmitter 14 connected to an antenna 15. V The pickup transmitter 10 is included in a series circuit comprising an electric supply source 16 represented as a battery, and a primary winding of speech transformer 17. The secondary winding of transformer 17 is shunted by potentiometerfresistance 18.

Thepotentlometer resistance18 is adapted to be variably included in the input circuit of space discharge amplifier 21 in series with a polarizing potential source 20, by ,means of adjustable contact arm 19. The

input circuit of this amplifier 21 includes its control electrode and cathode. The output circuit thereof includes its anode and cathode ,inseries withuthe primary winding of output transformer 22- and space'current source The secondary winding of transformer 22 has its terminals'connected tothe respective input terminals of an amplifier 24:, which may be of any desired type but. is preferably a space discharge amplifieniin general like thatdescribed in Patent 1, l4l8 ,550 to Arnold issued March 13, 1923. i

:The output terminals of the amplifier are connected to-a transmission line 12 which v may be for example, an ordinary telephone line, or a toll telephone line including repeaters having limited signal volume. ca-

pacity, theremote terminals of which are connected to the terminals of potentiometer resist-ance25 associated with potentiometer 1-3. This resistance may be adjustably in cluded in the input circuitof an amplifier '26,

which is identical withthe circuit of amplifier 21 and accordingly Will not be described in detail The output transformer 27 for the amplifier 26 has its secondary winding connected to the respective input terminals of a radio transmitter 1st which may include space discharge devices arranged in any one of many well'known forms, for example, as describedin Patent 1,442,147 toHeising issued January 16, 1923.

In the operation of the cireuitof Fig. 1,

sound waves, corresponding to speech, music or other similar sources, are supplied to pickup transmitterlO. The waves produced by thistransmitter are then supplied through transformer 17 and produce corresponding voltage changes in the-resistanceelements 18 of potentiometer 11. Corresponding voltage changes are therefore supplied to the input circuit of space discharge tube amplifier 21. The volume ofthe waves transmitted-through potentiometer 11 may be controlled by suitable adjustment of the-arm 19- so as tomaintain the signal volume at such value asnot to overload the amplifier 21, the amplifier 24 or the line 12. The waves, transmitted from amplifier 21, are supplied through transformer 22 to the amplifier-2 land thus are transmitted overline 12 to potentiometer 13. By means of the adjustment of the arm 28 of potentiometer 13, the volume of the received waves may be restored to the volume of waves originally supplied through transformer 17 from the transmitter 10.

Vfaves from the potentiometer 13 are supplied to the input circuit of amplifier 26 and after amplification are suppliedby transformer 27 to the radio transmitter 14. Accordingly, the waves radiated from the antenna'15retain the volume characteristics of the original sounds supplied to source 10 unimpaired by the volume control operations'effected at potentiometers 11 and '13.

In Fig. 2,the potentiometer control devices are illustrated. A senderswitch 30 includes a rotatable contact arm 31, adapted to pass overand electrically engage 'a plurality of contacts32 and 33 arranged in a circle. Attached to but insulated from, the contact arm 31 are individually insulated contact arms 34 and 35., The arms 34 and 35 are pivoted to a'hub'mountedon a central shaft 38. andv are attached to the arm 31 by means of insulated compression springs 36 and 37, respectively. The several arms arerotatable about a central post 38. "The arms 34 and 35 are preferably insulated from the central post 38 but are adapted to have enough frictionto resist rotation sufiiciently to enable contact with the arm 31.' The arm 31 is'preferably in electrical contactwith the central post 38 but adaptedoto freely rotate on it. Consequently, when'the arm 31 is rotated to the right it engages the contact 34, when it moves'. to theleftitengages-the contact 35 and when it is released itis moved by the action of compression springs-36 -:and 37 to a normal position outof contact with both the arms 3land 35.

The contact elements 32 and '33 may be mounted alternately upon an. insulating base 39. The contacts 32 have no connection. The contacts 33, however, areall connected to a'eommon lead extending to a line 40. A keyl, normally opened, is adapted to shunt the path between arms 31 and 34. The contact arm 31 and the central post 38 are coir nected to another line 42. Another normally opened key 43 is adapted to shunt the path including arms 31 and 35. The contacts 34 and 35 are connected to respective positive and negative poles of batteries 44 and 45, the respective negative and positive poles of which are connected together and to ground. The stationary contacts on keys 41 and 43 are connected respectively to the positive, and negative poles of batteries 44 and 45 as illustrated.

The sender switch 30 may be located at any desired point. It may be in the same location as one of the switches 50 and 51 or in any other suitable location remote therefrom.

The line 40 extends through the windings of release magnets 46 and 47 of rotary switches 50 and 51 respectively in series to ground. The line 42 likewise extends through solenoid magnets 48 and 49 of these switches in series to ground. The magnets are mounted upon permanently magnetized yoke members 7 0.' Themagnet 46 and sole noids 48 and their associated armatures 65 and 61, respectively, constitutethe release and driving mechanisms of switch 50, whereas magnet 47and solenoids 49 constitute the corresponding mechanisms of switch 51. Switch 50 corresponds to potentiometer 11 of Fig. 1 and switch 51 corresponds to potentiometer 13.

Theswitch 50 includes a circular ratchet 52, the rotation of which is controlled by a pawl 53, which is restrained by spring 54 and adapted to be operated by the magnet 46. The ratchet 52 is keyed to a shaft 55 which, supports a rotatable switch arm 19 and carries a gear wheel 57. The gear meshes with a toothed sector 58, which is connected by an eccentric pivot to the common armature 61 of the solenoids 48, and which is adapted to rotate about a fixed pivot 59.

The gear 57 is keyed to the shaft 55, but the wiper arm 19 is freely rotatable about the shaft. There is also keyed to the shaft 55 a driving arm 62 carrying an axial pin 63 which extends through an are shaped slot 64 in the wiper arm 19.

When the shaft is rotated by the driving gear the. pin rotates the arm 19 over its arc of contacts. The arm may if desired make direct contact with the resistance element 18 of the potentiometer. The switch 51 may also have its contact arm similarly arranged.

The slot is designed to allow sufficient play between the arm 62 and the wiper arm 19 to compensate for the necessary rotation of the ratchet 52, uncontrolled by the magnet 46, when the direction of the rotation of the ratchet 52 is reversed. This free play equals the pitch between teeth on the ratchet minus the thickness of a pawl tooth'and a ratchet tooth. The necessity for this play will be understood by a consideration of the positions of the ratchets illustrated on the motors 50 and 51. The ratchet 52 of motor 50 is illustrated as stopped after a rotation in a counter clockwise direction, whereas the ratchet 52 of motor 51 is illustrated as stopped following rotation in a clockwise direction.

The potentiometer resistances 18 and 25 may be included in the circuit of Fig. 1 within the dotted rectangles 11 and 13 whereby the volume may be controlled on the transmitting and receiving ends of the circuit simultaneously.

The circuit of Fig. 2 operates as follows: When arm 31 is rotated to the right it engages the contact arm 34 and also the successive contacts 33. There is, therefore, transmitted from battery 44 through arm 31 and successive contacts 33, over the line 40 to the magnets 46 and 47, a series of impulses of positive polarity, the number of which is determined by the number of contacts 33 engaged by the arm 31. At the same time, there is transmitted from battery 44 a continuous positive impulse of current over line 42 to the solenoids 48 and 49.

The windings of solenoids 48 may be so arranged that for positive impulses on the line 42, the armature 6'1 tends to move to the right, whereas the solenoids 49 preferably have their windings so arranged that the armature 61 tends to move to the left. Accordingly, at each impulse received by magnets 46 and 47, the pawls 53 and 53 are caused to oscillate by virtue of the successive attraction and release of the associated armatures 65 and 66 by the magnets 46 and 47. The respective ratchets 52 and 52 are thereby allowed to rotate at each oscillation of the pawl a distance equal to the distance between adjacent teeth. One half of this movement takes place when the respective armatures 65 and 66 are attracted and the other half takes place when the respective armatures are released. The wiper arms 19 and 28 may therefore, be stepped from contact to contact, on the associated arcs as the wiper 31 steps to successive contacts 32. Thereby the adjustment of the associated potentiometer may be effected. An important advantage of this invention is that by arranging for the synchronous movement of the control wiper arm and the remote switch arm the operator is notified of the condition of the potentiometers at all times.

When it is desired to adjust the potentiometers in the opposite direction, armature 31 of the sender switch 30 will be rotated in a counter clockwise direction. Accordingly, the arm 31 will engage contact 35 and negative impulses will be transmitted to the solenoid magnets 48 and 49. On account of the position of the pawls 53 and 53, the ratchets '52 and 52"Will immediately'rotate approximately thedistance of onetooth before the arm; 31 engages a' contact 33 connected to line .40.. This rotation of the" ratchets 52 and 1 52, however, produces no movement of the trol the movement of the arms 19 and 28 in the manner described for rotation in the opposite direction.

The keys 41 and 43 are provided toenable an adjustment of the switches without use of the switch 30. This may be desirable to obtain an initial synchronization of the switches and 51 with the switch 30.

The lines 40 and 4e2may be, for example, ordinary-telephone conductors or they'may be the telegraph circuits associated with a composite system or derived from a phantom circuit in a manner well understood.

This invention has the advantage that it enables positive adjustment of potentiometers or other devices located at widely sep arated points of any'amount andin any direction and, although the mechanism described hasbeen illustratedin connection with I 1y responsiveto'said positive or negative impulses for determining the directionof ror tation' of said ratchet, and means controlled by electrical impulses for determining'the number of operations of said pawl.

2. A circuitcont-rolapparatus comprising a rotary switch includin a rotatable ratchet and a release pawl thereror, a source of posi-' tive and negative'impulses, means differently responsive to said impulses for driving said ratchet'in either direction, and means for operating said pawl, a control switch connected to said source, and means for transmitting impulses from said switch'to both said ratchet driving means and pawl operating means whereby the direction of rotation and the degree of angular movement of said ratchet may be controlled. V

3. A circuit control apparatus comprising a rotary switch,.a control device and a source of actuating current therefor, said switch comprising a plurality of contact elements arranged in an arc, a slotted rotatable wiper arm adapted to rotate over said are of contacts, means for driving said wiper arm in either direction comprising a ratchet, said ratchet having a certainamount of free play when its direct-ion of rotation is reversed, and means for preventing movement of said wiper arm when said ratchet moves under free play, comprising another arm attached to said ratchet and carrying a pin inserted in a slot in said wiper arm. 1

4. In an electric control system, a plurality of rotatable switches, respective driving magnets there-for for rotating said switches in either direction as determined by the polarity of the current impulses applied thereto, release magnets associated with said switches,

and means for supplying positive or negative impulses to said driving magnets 'to'cause their. simultaneous operation, said driving magnetsbeing so arranged as'tomove said respective switches'in opposite directions for current impulses of the same polarity, and means for supplyingv impulses to said release magnets to cause their simultaneous operation, V

5. A radio broadcasting system, having a line associated therewith, atransmitting circuit and a receiving circuit included in said line, separate'volume control means in said transmitting circuit and in said receiving circuit, and means for operating said volume control means in unison, comprising individual-motors having driving and release mechanisms, means to supply current impulses in common to said'driving mechanisms for causing their operation in onset two directions and'means to supply a series of impulses to said release mechanism for determining the extent of movement of said motors. V

l 6. A radio broadcasting system, comprising a line having separate paths at its transmitting and receiving terminals, a volume varying device in said-transmitting path, and a volume varying device in said receiving path, and means for simultaneously controlling said volume varying devices to-produce equal and opposite changes in volume in said paths, comprising separate motor devices,

having driving means and releasing means, a manually operated switch, a line connecting said switch to said releasing means, and a line connecting said switch to said driving means,said switch being adapted to transmit positive or negative impulses over said line to said respective driving and releasing means.

7 In a-broadcasting-system, a sound pickup station including a space discharge tube amplifier, :1 radio transmitting station including a space discharge tube amplifier, a wire line connecting said pick-up station to said radio-transmitting station, a volume-control potentiometer includedin input circuits of each'ofsaid amplifiers, means for causing simultaneous operation'of said potentiometers for varyingthe volume of the transmitted waves in opposite senses, comprising a manual switch, a rotatable wiper arm associated with each of said potentiometers, separate driving mechanisms for said arms including solenoids arranged in a series circuit, and separate release mechanisms for said arms including electromagnets also arranged in a series circuit, said circuits each including said manual switch, whereby simultaneous movement of said driving mechanisms, in opposite directions, may be controlled by said switch.

In Witness whereof, I hereunto subscribe my name this 12th day of November A. D.,

JOHN C. BURKHOLDER. 

